X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FBasicTargetTransformInfo.cpp;h=b2737bf754f9e39761683e73239016a209f5524f;hb=d2ce9392dca6349a22c8f3e21e74aa59a82d8900;hp=e3ecf14d1f2ff3737043b05f29042ec4f4269ec1;hpb=3b89e528c421f98f3555d7d8f4072328259480a0;p=oota-llvm.git diff --git a/lib/CodeGen/BasicTargetTransformInfo.cpp b/lib/CodeGen/BasicTargetTransformInfo.cpp index e3ecf14d1f2..b2737bf754f 100644 --- a/lib/CodeGen/BasicTargetTransformInfo.cpp +++ b/lib/CodeGen/BasicTargetTransformInfo.cpp @@ -15,14 +15,21 @@ /// //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "basictti" #include "llvm/CodeGen/Passes.h" +#include "llvm/Analysis/LoopInfo.h" #include "llvm/Analysis/TargetTransformInfo.h" +#include "llvm/Support/CommandLine.h" #include "llvm/Target/TargetLowering.h" +#include "llvm/Target/TargetSubtargetInfo.h" #include - using namespace llvm; +static cl::opt +PartialUnrollingThreshold("partial-unrolling-threshold", cl::init(0), + cl::desc("Threshold for partial unrolling"), cl::Hidden); + +#define DEBUG_TYPE "basictti" + namespace { class BasicTTI final : public ImmutablePass, public TargetTransformInfo { @@ -32,10 +39,13 @@ class BasicTTI final : public ImmutablePass, public TargetTransformInfo { /// are set if the result needs to be inserted and/or extracted from vectors. unsigned getScalarizationOverhead(Type *Ty, bool Insert, bool Extract) const; + /// Estimate the cost overhead of SK_Alternate shuffle. + unsigned getAltShuffleOverhead(Type *Ty) const; + const TargetLoweringBase *getTLI() const { return TM->getTargetLowering(); } public: - BasicTTI() : ImmutablePass(ID), TM(0) { + BasicTTI() : ImmutablePass(ID), TM(nullptr) { llvm_unreachable("This pass cannot be directly constructed"); } @@ -187,7 +197,61 @@ bool BasicTTI::haveFastSqrt(Type *Ty) const { return TLI->isTypeLegal(VT) && TLI->isOperationLegalOrCustom(ISD::FSQRT, VT); } -void BasicTTI::getUnrollingPreferences(Loop *, UnrollingPreferences &) const { } +void BasicTTI::getUnrollingPreferences(Loop *L, + UnrollingPreferences &UP) const { + // This unrolling functionality is target independent, but to provide some + // motivation for its intended use, for x86: + + // According to the Intel 64 and IA-32 Architectures Optimization Reference + // Manual, Intel Core models and later have a loop stream detector + // (and associated uop queue) that can benefit from partial unrolling. + // The relevant requirements are: + // - The loop must have no more than 4 (8 for Nehalem and later) branches + // taken, and none of them may be calls. + // - The loop can have no more than 18 (28 for Nehalem and later) uops. + + // According to the Software Optimization Guide for AMD Family 15h Processors, + // models 30h-4fh (Steamroller and later) have a loop predictor and loop + // buffer which can benefit from partial unrolling. + // The relevant requirements are: + // - The loop must have fewer than 16 branches + // - The loop must have less than 40 uops in all executed loop branches + + // The number of taken branches in a loop is hard to estimate here, and + // benchmarking has revealed that it is better not to be conservative when + // estimating the branch count. As a result, we'll ignore the branch limits + // until someone finds a case where it matters in practice. + + unsigned MaxOps; + const TargetSubtargetInfo *ST = &TM->getSubtarget(); + if (PartialUnrollingThreshold.getNumOccurrences() > 0) + MaxOps = PartialUnrollingThreshold; + else if (ST->getSchedModel()->LoopMicroOpBufferSize > 0) + MaxOps = ST->getSchedModel()->LoopMicroOpBufferSize; + else + return; + + // Scan the loop: don't unroll loops with calls. + for (Loop::block_iterator I = L->block_begin(), E = L->block_end(); + I != E; ++I) { + BasicBlock *BB = *I; + + for (BasicBlock::iterator J = BB->begin(), JE = BB->end(); J != JE; ++J) + if (isa(J) || isa(J)) { + ImmutableCallSite CS(J); + if (const Function *F = CS.getCalledFunction()) { + if (!TopTTI->isLoweredToCall(F)) + continue; + } + + return; + } + } + + // Enable runtime and partial unrolling up to the specified size. + UP.Partial = UP.Runtime = true; + UP.PartialThreshold = UP.PartialOptSizeThreshold = MaxOps; +} //===----------------------------------------------------------------------===// // @@ -266,8 +330,28 @@ unsigned BasicTTI::getArithmeticInstrCost(unsigned Opcode, Type *Ty, return OpCost; } +unsigned BasicTTI::getAltShuffleOverhead(Type *Ty) const { + assert(Ty->isVectorTy() && "Can only shuffle vectors"); + unsigned Cost = 0; + // Shuffle cost is equal to the cost of extracting element from its argument + // plus the cost of inserting them onto the result vector. + + // e.g. <4 x float> has a mask of <0,5,2,7> i.e we need to extract from index + // 0 of first vector, index 1 of second vector,index 2 of first vector and + // finally index 3 of second vector and insert them at index <0,1,2,3> of + // result vector. + for (int i = 0, e = Ty->getVectorNumElements(); i < e; ++i) { + Cost += TopTTI->getVectorInstrCost(Instruction::InsertElement, Ty, i); + Cost += TopTTI->getVectorInstrCost(Instruction::ExtractElement, Ty, i); + } + return Cost; +} + unsigned BasicTTI::getShuffleCost(ShuffleKind Kind, Type *Tp, int Index, Type *SubTp) const { + if (Kind == SK_Alternate) { + return getAltShuffleOverhead(Tp); + } return 1; } @@ -298,7 +382,8 @@ unsigned BasicTTI::getCastInstrCost(unsigned Opcode, Type *Dst, return 0; // If the cast is marked as legal (or promote) then assume low cost. - if (TLI->isOperationLegalOrPromote(ISD, DstLT.second)) + if (SrcLT.first == DstLT.first && + TLI->isOperationLegalOrPromote(ISD, DstLT.second)) return 1; // Handle scalar conversions. @@ -405,7 +490,9 @@ unsigned BasicTTI::getCmpSelInstrCost(unsigned Opcode, Type *ValTy, unsigned BasicTTI::getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index) const { - return 1; + std::pair LT = getTLI()->getTypeLegalizationCost(Val->getScalarType()); + + return LT.first; } unsigned BasicTTI::getMemoryOpCost(unsigned Opcode, Type *Src, @@ -414,8 +501,32 @@ unsigned BasicTTI::getMemoryOpCost(unsigned Opcode, Type *Src, assert(!Src->isVoidTy() && "Invalid type"); std::pair LT = getTLI()->getTypeLegalizationCost(Src); - // Assume that all loads of legal types cost 1. - return LT.first; + // Assuming that all loads of legal types cost 1. + unsigned Cost = LT.first; + + if (Src->isVectorTy() && + Src->getPrimitiveSizeInBits() < LT.second.getSizeInBits()) { + // This is a vector load that legalizes to a larger type than the vector + // itself. Unless the corresponding extending load or truncating store is + // legal, then this will scalarize. + TargetLowering::LegalizeAction LA = TargetLowering::Expand; + EVT MemVT = getTLI()->getValueType(Src, true); + if (MemVT.isSimple() && MemVT != MVT::Other) { + if (Opcode == Instruction::Store) + LA = getTLI()->getTruncStoreAction(LT.second, MemVT.getSimpleVT()); + else + LA = getTLI()->getLoadExtAction(ISD::EXTLOAD, MemVT.getSimpleVT()); + } + + if (LA != TargetLowering::Legal && LA != TargetLowering::Custom) { + // This is a vector load/store for some illegal type that is scalarized. + // We must account for the cost of building or decomposing the vector. + Cost += getScalarizationOverhead(Src, Opcode != Instruction::Store, + Opcode == Instruction::Store); + } + } + + return Cost; } unsigned BasicTTI::getIntrinsicInstrCost(Intrinsic::ID IID, Type *RetTy, @@ -460,7 +571,7 @@ unsigned BasicTTI::getIntrinsicInstrCost(Intrinsic::ID IID, Type *RetTy, case Intrinsic::round: ISD = ISD::FROUND; break; case Intrinsic::pow: ISD = ISD::FPOW; break; case Intrinsic::fma: ISD = ISD::FMA; break; - case Intrinsic::fmuladd: ISD = ISD::FMA; break; // FIXME: mul + add? + case Intrinsic::fmuladd: ISD = ISD::FMA; break; case Intrinsic::lifetime_start: case Intrinsic::lifetime_end: return 0; @@ -485,6 +596,12 @@ unsigned BasicTTI::getIntrinsicInstrCost(Intrinsic::ID IID, Type *RetTy, return LT.first * 2; } + // If we can't lower fmuladd into an FMA estimate the cost as a floating + // point mul followed by an add. + if (IID == Intrinsic::fmuladd) + return TopTTI->getArithmeticInstrCost(BinaryOperator::FMul, RetTy) + + TopTTI->getArithmeticInstrCost(BinaryOperator::FAdd, RetTy); + // Else, assume that we need to scalarize this intrinsic. For math builtins // this will emit a costly libcall, adding call overhead and spills. Make it // very expensive.